Terminal voltage analysis for the transformerless PV inverter topologies in a single‐phase system

Abstract

This study presents an analysis of the terminal voltage of the basic photovoltaic (PV) inverter topologies available in the literature. The presented analysis utilises the switching function concept. Use of switching function in the analysis enables the inclusion of the effect of the pulse-width modulation technique or the switching strategy on the terminal voltage of the reviewed configuration. It gives insight into the switching action effects on the terminal voltage and provides every detail of the high-frequency transitions in the terminal voltage for the given switching strategy. Using the terminal voltage expression derived in terms of switching function, the analytical waveforms are obtained for various configurations. These waveforms are compared with the simulation and experimental results waveforms to justify the analysis given. This study also presents a bar chart view of the switching and conduction losses of the switches in the reviewed PV inverter topologies. The magnitude of high-frequency components in the terminal voltage and the leakage current is also presented in this study. The PV inverter topologies are also compared in terms of other aspects such as a number of devices used, asymmetry in operation, filter requirement etc.

Single-Phase Five-Level Transformerless PV Inverter for the Alleviation of Common Mode and Leakage Currents by Accounting the Effect of Device Junction Capacitance

“…The terminal voltage is a function of the common mode and the grid voltage. The common mode is the average of the inverter pole voltages [12]. Usually while calculating the inverter pole voltages, the effect of the junction capacitance across power semiconductor switches that are in the turn OFF state is neglected.…”

“…Usually while calculating the inverter pole voltages, the effect of the junction capacitance across power semiconductor switches that are in the turn OFF state is neglected. But practically it can affect inverter pole voltages during turn OFF condition typically in case of DC decoupled configuration [12]. Discontinuity in the terminal and CMV waveform, can be attributed to the effect of DJC during turn-off state.…”

“…The expression for vyg and vzg in terms of vg is given by [12] yg zg g v v v += (14) Equating ( 13) and ( 14) gives 0 5 0 5 0 5…”

An improved nine‐level switched capacitor‐based inverter with voltage boosting capability and limitation of capacitor current spikes for PV applications

“…Among these solutions, integration of renewable energy sources (RESs) into power systems is one of the most popular and widely accepted solutions. At the large family of RESs, photovoltaic (PV) systems are of the widely used members [4][5][6]. However, to employ and integrate these sources into the power systems, power electronic based interfaces, that is, power converters, are inevitable [7][8][9][10].…”

Leakage current alleviation in solar energy conversion system enabling power quality improvement

“…Various topologies are described in [3,[8][9][10] to alleviate the leakage current issue in the transformerless grid-interfaced SECS. To address the aforementioned issue, highly reliable inverter concepts (HERIC), H-bridge, H5, H6 converter, and zero voltage regulation (ZVR) topologies are presented in [1,11,12]. The integration of the solar PV array system with a single-phase grid causes the undesired power oscillations and unbalanced problems under high penetration of renewable power generation.…”